This invention relates to containers for liquids, and in particular to an integral closure for the container which is formed in the container end.
Beverage containers are typically provided with an opening means for removal of the container contents. A wide variety of closures for containers for the packaging of beer, soft drinks and other liquids have a portion of the lid which is torn away along score lines to open the container. To facilitate removal of the tear away portion, a separate tab is secured to the container lid at the point at which the tearing operation is to be initiated. The tab is lifted by a finger and used as a handle to remove the tear away portion. Any such known arrangement requires a two-part assembly.
Until recently, a widely used "pop-top" permitted and envisaged the complete removal of a portion of the lid to provide the opening. Because of the nuisance of disposal of the removed tab, many users simply drop the tab into the opened container. Not only does this practice introduce contaminants into the container, but also it may result in injury to those drinking directly from the can as a consequence of passage of the metal tab out of the container as the contents are being drunk by the user. As a consequence, the sale of containers having this popular form of closure has been prohibited in many jurisdictions and a more costly, non-removable pop-top design has been substituted. However, this design, in addition to being more costly, also is difficult to manipulate to open the container and it frequently malfunctions so that the container must be opened by other means.
Other pop-tops for containers have been developed. For example, U.S. Pat. No. 3,741,432 discloses a container having a closure tab and pressure release tab. Such tabs were previously utilized in beer containers sold in the latter part of the 1970's throughout the Western United States, but were discontinued due in part to considerable difficulties experienced by users in opening the containers. In addition, the closure is unsatisfactory since the closure must be bent inwardly into the container and is therefore a potential source of contamination.
Other closures have been developed for containers. For example, U.S. Pat. No. 3,843,011 discloses several embodiments of a closure for a container. However, each of the disclosed closures is complex (and therefore costly) and requires several steps in manufacture. U.S. Pat. No. 3,261,497 discloses a closure for a container having a folded-over portion which is hingedly secured to the top end of the container. Again, due to the complexity of the closure, its use is not feasible in light of manufacturing and assembly costs.
U.S. Pat. No. 3,958,717 discloses a container closure which is hinged to be bent downwardly into the interior of the container. Not only is the closure a potential source of contaminants for the container, but also since the closure is secured to only a small portion of the container body, the remainder of the periphery of the closure must be sealed by a bead of plastic sealing material. This increases cost and is potential source of failure of the closure.
Various other closures are disclosed in U.S. Pat. Nos. 3,250,426; 3,472,415; 3,871,552; 3,887,105 and 3,889,842. Each of the closures is complex requiring a separately attached tab or separately applied seal which increases the cost of manufacture of the container closure.